This invention relates to a hybrid integrated circuit component, a printed circuit board on which said component is mounted, and a method of mounting the component on the board.
Recently, the need for compact, lightweight electronic equipment of various kinds, such as video equipment, has been increasing remarkably. The challenge, therefore, is to achieve miniaturization and high density of electric circuit boards which constitute such equipment. A number of methods have been adopted as a means to achieve miniaturization and high density of circuit boards for various electronic equipment. One such method is to divide the entire circuit into several blocks to highly integrate each block to create a module, which is then fitted on a mother printed circuit board together with other circuit elements and connected with each other, thereby constituting a circuit substrate.
These highly integrated circuit block modules, generally called hybrid integrated circuit components, are widely used for a variety of electronic equipment. They have played an important role in achieving not only compactness and lightness of weight but also high performance of the electronic equipment.
The conventional hybrid integrated circuit component, which has been entertaining widest acceptance is composed of a so-called "thick film circuit substrate", or alumina substrate 1, on the surface of which silver-type circuit conductors 2 and resistors are formed by means of printing; on which circuit elements 3, e.g. layered ceramic condensers, resin-moduled transistors, and integrated circuit components such as semiconductor ICs are mounted and electrically connected to form a block circuit; and which is equipped with lead wires 4 as external connection terminals. However, the above-mentioned hybrid integrated circuit component had the following disadvantages:
(1) A high density circuit is hard to materialize therefrom since the circuit block is provided on one side of the alumina substrate. Even if high density is achieved by constructing circuit blocks on both sides of the alumina substrate, the manufacturing process is very complicated and makes the component far from economical.
(2) Since lead wires are used as external connection terminals, the reliability of connection between the circuit block and lead wires is insufficient.
(3) The use of lead wires as external connection terminals hampers integration of the circuit due to complicated nature of the connection work as well as the need to provide space on the substrate constituting the block circuit for connection of lead wires.
(4) Since lead wires are used as external connection terminals, the block circuit protrudes from the level of the mother printed circuit board when mounted on the mother printed circuit board, thereby preventing the circuit substrate from being made thinner.
(5) Since an alumina substrate is used, the dimensions of the circuit block are constrained due to the limited mechanical strength of the substrate.
(6) Since a number of lead wires are connected, insertion of the terminals into the slot in the mother printed circuit board becomes difficult especially when the slot is small. On the other hand if the slot is large enough, the circuit block "floats" from the mother printed circuit board at the time of soldering.
These disadvantages have been the major obstacles to achieving miniaturization and high density of circuit substrates and improving reliability.
This invention eliminates all the above-mentioned problems.
Accordingly, an object of the present invention is to provide a hybrid integrated circuit component best suited for compact and lightweight electronic equipment.
Another object of the present invention is to provide a hybrid integrated circuit component best suited for highly reliable electronic equipment.
Still another object of the present invention is to provide a printed circuit board on which such a component is mounted, which is best suited for compact, lightweight, and highly reliable electronic equipment.
A further object of the present invention is to provide mounting methods of such a hybrid integrated circuit component on such a printed circuit board .